The present invention relates generally to data networks, and more particularly to estimating round trip path segment delay in a data network.
Quality of Service (QoS) is becoming increasingly important to e-commerce companies doing business over the Internet (or other data networks). Such companies offer various services to their customers over the Internet, including the ability to perform commercial transactions. These companies generally maintain one or more web servers which provide the online functionality to their customers. The connectivity of these web servers to the Internet is provided by Internet service providers (ISP). Since much of the success of an e-commerce company depends upon the quality of the connection of their web servers to the Internet, such companies are interested in negotiating service level agreements (SLA) with their ISPs. An SLA defines the level of service which the ISP will provide to the company and may guarantee some minimum QoS to the e-commerce company.
The increasing popularity of SLAs then raises the issue of how to enforce an SLA and how to monitor the QoS being provided to the e-commerce company by the ISP. Perceived network congestion may be due to various network elements, some of which may be the responsibility of the ISP under the SLA, and others of which are not the responsibility of the ISP and not guaranteed by the SLA. Thus, the mere detection of end to end network delay does not necessarily implicate the SLA, as the ISP may not be the party responsible for the portion of the network causing the delay.
An e-commerce company may monitor the QoS being provided by an ISP under an SLA, or the e-commerce company may engage the services of a third party to monitor the QoS being provided by the ISP. Either way, the party monitoring the service is not the network service provider, and therefore does not have access to all of the network diagnostic tools at the disposal of the network provider. As such, it is generally difficult for a third party observer to accurately pinpoint the portion of a data network causing delays.
There is a need for a technique which allows a third party observer to detect congestion in a data network and to be able to determine which network path segments, or particular links, are the cause of network delays.